Field of the Invention
The present invention relates to a method for producing a pneumatic tire for heavy load, the method including a vulcanizing step of: putting, into a mold, an unvulcanized raw tire having a pair of bead regions, a side wall region extended from each of the bead regions outward along the tire diameter direction, and a tread region connected to an outside end in the tire diameter direction of each of the side wall regions, the tread region constituting a tread of the tire; and then heating and vulcanizing the raw tire while a bladder inside the raw tire is expanded to put and press the raw tire onto the inner surface of the mold.
Description of the Related Art
In pneumatic tires for heavy load, which are used in trucks, buses, vehicles for construction, and the like, their sites where trouble is caused are typically their tread region and bead regions. A method for improving these regions in endurance is, for example, a method of adding a reinforcing member to desired positions thereof, or a method of contriving the shape thereof. However, such a method may result in an undesired increase in the mass or in costs, or the like.
In order to prevent local overcure of a tire casing-region including an inner liner layer or a carcass layer to improve the tire in endurance, Patent Document 1 below describes a method for producing a pneumatic tire in which regarding respective highest reach-temperatures of individual positions in the thickness direction of a crown region of a tire while the region is being vulcanized, the difference between a maximum value and a minimum value of the temperatures is set to 10° C. or lower, and further regarding respective equivalent vulcanization degrees of the individual positions in the thickness direction of the tire crown region, the ratio of a maximum value of the degrees to a minimum value thereof is set to 1.6 or lower.